1. Field of the Invention
The present invention relates to a disc apparatus having a DC motor which rotates a disc.
2. Description of the Related Art
In a disc apparatus which rotates a disc such as CD, CD-R, DVD or the like by using a DC motor such as a spindle motor to record and reproduce images and so on, dust particles are sometimes generated due to an abrasion of a brush in the DC motor and cause a short circuit of a commutator in the DC motor. When the commutator is short-circuited, the spindle motor stops rotating, and the disc thereby stops rotating. When the disc stops rotating, a controller which controls the disc apparatus increases an output current of a drive IC which drives the DC motor to speed up a rotation speed of the spindle motor. The drive IC produces heat due to the increase of the output current. The heat may cause a malfunction of the drive IC and a large current flowing through an actuator. Moreover, when the disc stops rotating, the controller gets less able to obtain an accurate operation of the actuator. As a result, the controller forces the drive IC to operate to rotate the disc. In this case, the drive IC passes the large current through the actuator and consequently, a cover of the actuator sometimes burns.
In Japanese Laid-Open Patent Publication No. 2003-174795, there is a disclosure of a technique to detect a failure caused by a short circuit in a field-effect transistor which performs a drive control of a motor when the motor starts driving and stops.
Although the technique described in 2003-174795 enables the detection of the failure caused by the short circuit in the field-effect transistor, it does not enable a detection of a failure caused by a short circuit in a motor.
The present invention is to solve the problem described above, and an object of the present invention is to provide a disc apparatus having a spindle motor to rotate a disc which can judge accurately whether or not the spindle motor is at fault due to a short circuit and also prevent the spindle motor from driving in case of failure in the spindle motor due to the short circuit.